Mortiser

ABSTRACT

A mortiser has a housing mounted on a support post and there is a collet on the housing for holding a mortise chisel. A chisel drive coupling is on the housing. A chisel drive shaft extends through the housing and connects with the chisel drive coupling. A reciprocal engagement mechanism is capable of selectively engaging the chisel drive coupling. An operating lever may thus be quickly indexed so that the mortise chisel may be filly lowered without the user pulling the operating lever fully toward him/her and downward. The mortiser also has a finely adjustable ram fence and a depth stop. The collet has a notched or elliptical bore to prevent jamming of the chisel shank in the collet.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from U.S. Provisional Patent Application Serial No. 60/292,770, filed May 22, 2001, and entitled “Mortiser.”

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is directed to machines capable of making a mortise cut into wood and, more particularly, to mortising machines.

[0004] 2. Brief Description of the Prior Art

[0005] A mortise is a rectangular cavity cut into or through a piece of wood. Achieving this type of cut has been accomplished by various means. For example, round holes can be drilled into the wood, which are subsequently “squared off” through the use of a mortising chisel. On the other hand, a mortising knife and a mortising chisel can be used directly to form the rectangular cavity cut into the wood. This type of mortising can be very imprecise and labor intensive.

[0006] In order to minimize the effort involved and improve the accuracy of cutting a mortise, mortising machines were developed. These were typically in two forms, adaptations of other pieces of woodworking equipment (drills, routers, etc.) and mortising machines that directly cut a mortise using a hollow square or rectangular mortise chisel. In most cases, the level of effort required to cut a mortise was improved, but the accuracy of the mortise was not.

[0007] A common disadvantage of electric-powered chisel mortisers is that the action and heat generated from making the mortise cut causes the mortise chisel to become “stuck” in the chuck of the mortiser. In effect, the shank end of the mortise chisel becomes very difficult to remove from the chuck. A “stuck” mortise chisel creates obvious disadvantages regarding poor efficiency and inconvenience.

[0008] Electric-powered chisel mortisers are limited as to the depth of the mortise cut that can be made. This limitation often occurs when an arm is used to lower the motor, chuck, and mortise chisel into a work piece. The arm can only be moved by pulling the arm from an upper position to a lower position. Once the lower position is reached, the mortise chisel can be lowered no further, and a finite depth of a mortise cut is reached. Also, it may be awkward for the user to fully pull the lever toward him to achieve the desired deep mortise cut.

[0009] There is a need for an electric-powered mortiser in which mortise chisels do not become “stuck.” It is also desirable to expand the depth of mortise cuts that can be achieved using an electric-powered mortiser. Finally, it is desired to facilitate fine adjustments of the position of a work piece on a table of the mortiser, using an adjustable fence.

SUMMARY OF THE INVENTION

[0010] The present invention has several aspects generally related to abrading machinery which is configured to vertically engage and disengage a cutting tool with a work piece. First, the invention is directed to a mortiser for making a mortise cut in a work piece. The mortiser having a base, a table mounted on the base, a housing supported above the base, and a collet connected with the housing for receiving a mortise chisel shank. The mortiser includes a motor, with a chisel drive shaft extending through the housing and a chisel drive coupling attached to the chisel drive shaft. A collet lowering mechanism is connected with the chisel drive shaft, and a reciprocal engagement mechanism is capable of selectively engaging the chisel drive coupling. An operating lever is attached to the reciprocal engagement mechanism for rotating the chisel drive shaft and for reciprocating the reciprocal engagement mechanism into and out of engagement with the chisel drive coupling. When the coupling and reciprocal engagement mechanism are engaged, and an operator pulls the lever, the chisel drive shaft and the collet lowering mechanism cooperate to lower the collet toward the work piece.

[0011] The invention also includes a method of abrading a work piece using a motorized machine which is configured to vertically engage and disengage a cutting tool with the work piece. The method comprises the steps of positioning the work piece below the cutting tool and engaging an operating lever with a drive coupling on the machine, the drive coupling mechanically interconnected with the cutting tool so as to permit upward and downward movement of the cutting tool. The cutting tool is then lowered a first increment toward the work piece by pulling the lever from a first position to a second position. Later, the lever is disengaged from the drive coupling and repositioned to the first position. The lever is then reengaged with the drive coupling, and the user then further lowers the cutting tool a second increment by again pulling the lever from the first position to the second position.

[0012] The invention is also directed to a mortiser for making a mortise cut in a work piece. The mortiser having a base, a table mounted on the base and a housing supported above the base. A collet extends downward from the housing for receiving a mortise chisel shank, and the mortiser has a motor. A mechanism for raising and lowering the collet is provided, and according to this aspect of the invention, the collet has a chisel shank removal device in an interior bore of the collet to facilitate removal of the chisel shank from the collet. The chisel shank removal device may be a notch extending the length of the internal bore in the collet or it may comprise the internal bore of the collet having an elliptical shape.

[0013] Next, the invention comprises a machine for abrading a work piece. The machine having a base, a motor, a table mounted on the base, a housing supported above the base and a mechanism for holding a cutting tool extending downward from the housing. According to this aspect of the invention, the machine for abrading a work piece has an adjustable fence positioned on an upper surface of the table, with at least one fence ram assembly connected with the adjustable fence. The fence ram assembly comprises at least one positive stop slidably attached to a cylindrical ram. The assembly also includes a post having an internal bore, a set screw hole, and a set screw with a set screw handle. The cylindrical fence ram is journaled in the bore of the post and attached to the rear side of the adjustable fence. Preferably, the machine has two fence ram assemblies behind the adjustable fence.

[0014] These and other advantages can be found in the present invention and will be clarified in the description of the preferred embodiment taken together with the attached drawings in which like reference numerals represent like elements throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a front perspective view of the mortiser of the present invention;

[0016]FIG. 2 is a rear perspective view of the mortiser of the present invention particularly showing the microadjustable fence of the present invention;

[0017]FIG. 3 is a front elevational view of the mortiser of the present invention;

[0018]FIG. 4 is a right side elevational view of the mortiser of the present invention;

[0019]FIG. 5 is a schematic view of an engaged reciprocal engagement mechanism and chisel drive coupling according to the present invention;

[0020]FIG. 6 is a schematic view of the reciprocal engagement mechanism and chisel drive coupling of FIG. 5, but shown in a disengaged position;

[0021]FIG. 7 is a schematic view of a collet lowering mechanism of the present invention;

[0022]FIG. 8 is a cross section view of one collet according to the present invention;

[0023]FIG. 9 is a top view of the collet shown in FIG. 8;

[0024]FIG. 10 is a top view of another collet according to the invention; and

[0025]FIG. 11 is a bottom view of the mortiser of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] For the purpose of the description hereinafter, the terms “upper,” “lower,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” and derivatives thereof shall relate to the invention as oriented in the drawing Figures. However, it is to be understood that the invention may assume alternate variations and step sequences except where expressly specified to the contrary. It is also to be understood that the specific devices and methods, illustrated in the attached drawings and described in the following specification, are exemplary embodiments of the invention. Hence, specific dimensions and other physical characteristics related to the embodiment disclosed herein are not to be considered as limiting the invention.

[0027] In FIG. 1, a mortiser 10 has a motor 14, a housing 36, a reciprocal engagement mechanism 30, an operating lever 12, a notched post 46, a spring-loaded post 40, a table 18, a fence 22, and a base 38. Motor 14 utilizes electric power, which is supplied via transformer 44 in order to provide the required direct current and voltage for motor 14. Motor 14 includes a drive shaft (not shown) to which a chuck in the housing (also not shown) is attached. Collet 16 is adapted to receive a mortise chisel 17, and the chisel is fixed in place via a set screw (not shown) fixed via set screw hole 54 (FIG. 4). Particularly, set screw 54 engages a rim that extends downward from housing 36. Table 18 rests on top of base 38 and is moved in a left or right direction by a rack and pinion mechanism 21, which includes a table pinion 19 and a table rack 123 (as shown in FIG. 11). Table pinion 19 is in contact with and engaged with table rack 123. The rack and pinion mechanism 21 is driven by rack and pinion wheel 20, which communicates with the rack and pinion mechanism 21 by table adjust screw 58 (shown in FIG. 4). The mortiser 10 may be sized and designed to be used on a bench top or to be joined with a stand for floor installation.

[0028] Operating lever 12 has a handle end 90, onto which is placed a handle 34, a lever portion 88, and a drive end 92. Referring to FIG. 5, a lever insert 122 has a threaded portion 86 (covered by a nut 60 in FIG. 5), a pivot point 84, an insert end 126, and a terminal end 124. Insert end 126 is inserted into a hollow portion 91 of drive end 92 of operating lever 12. The threaded portion 86 begins at terminal end 124 and extends a distance along lever insert 122 sufficient to threadably attach nut 60. A portion of lever insert 122 passes through reciprocal engagement mechanism 30. A locking pin (not shown) may be placed through a locking pin channel 82 in lever insert 122. Reciprocal engagement mechanism 30 includes a body 70 engaged and in contact with a right chisel drive coupling 72 or a left chisel drive left coupling 74, a piston 114 located within body 70 and having a head 118 that abuts pivot point 84 on lever insert 122, a spring housing 77, and a spring 78 inside spring housing 77 covering a portion of piston 114. Spring 78 exerts pressure on piston head 118. Body 70 is thus biased into engagement with right coupling 72.

[0029] Returning to FIG. 1, housing 36 has a top side 100, a right side 96, a left side 104, a front side 94, a rear side 98, and a bottom side 102. Attached to rear side 98 of housing 36 is an accessory holder 64 (see FIG. 2).

[0030] Housing 36 (and collet 16) is moved vertically by the action of operating lever 12 and reciprocal engagement mechanism 30. FIG. 3 shows body 70 engaged with right coupling 72. FIGS. 5 and 6 show that body 70 has a grip end 108, and right coupling 72 has a grip end 106. Grip ends 106, 108 are constructed such that they can selectively interlock with a ratchet action (for example, by providing intermeshing teeth 109). The raised portions along grip end 106 fit within the recessed portions of grip end 108, and the raised portions along grip end 108 fit within the recessed portions of grip end 106. FIG. 3 shows a tooth grip 76 established between right coupling 72 and body 70.

[0031] Referring to FIGS. 5 and 6, body 70 engages right coupling 72 (shown) or left coupling 74 (shown in FIG. 3). Reciprocal engagement mechanism 30 can thus be in an engaged position 110 or a disengaged position 112.

[0032] Focusing on FIG. 5, reciprocal engagement mechanism 30 is in engaged position 110, which means that the raised portions along grip end 106 are intermeshed within the recessed portions of grip end 108, and the raised portions along grip end 108 are intermeshed within the recessed portions of grip end 106. Lever insert 122 passes through a channel 116 in body 70. Piston head 118 is held firmly and squarely against lever insert 122, directly opposite of pivot point 84 by spring 78. Piston 114 has a drive end 120 received in right coupling 72. Drive end 120 is inserted into a threaded piston channel 150 located within right coupling 72. A set screw (not shown) is threadably inserted into set hole 148 to secure right coupling 72 in place on drive shaft 80. A first washer 68, through which lever insert 122 passes, rests firmly against body 70 and is held in place by a lever spring 32. Lever spring 32 provides tension against first washer 68 and a second washer 66, through which lever insert 122 also passes. The pressure applied by lever spring 32 against second washer 66 holds it firmly against nut 60 and biases lever 12 in the upright position.

[0033] Mortiser 10 may be reconfigured for left-handed operation. This is accomplished by removing threaded piston 114 and body 70 from right coupling 72 and attaching it to left coupling 74. Body 70 is removed from right coupling 72 by loosening nut 60, withdrawing lever insert 122 and lever 12 from channel 116, and then unscrewing piston 114 via head 118. Body 70 is then attached to left coupling 74 by inserting drive end 120 of piston 114 into piston channel 150 of left coupling 74 and screwing in piston 114 to tighten. Lever insert 122 and lever 12 are then remounted in channel 116. When attached to left coupling 74, body 70 is operated as described with respect to right coupling 72, except the operator may then use his left hand.

[0034] When the reciprocal engagement mechanism 30 is in the engaged position 110, housing 36 can be lowered, for example, by an operator grasping handle 34 and pulling it in a generally forward and downward direction. This action through operating lever 12 and lever insert 122 causes body 70, coupling 72, and chisel drive shaft 80 to rotate counter-clockwise. Particularly, operating lever 12 is pulled from its substantially upright position (shown in FIG. 4) toward table 18 a first increment, so that lever 12 ends up in a more inclined position.

[0035] Turning to FIG. 7, a collet lowering mechanism 128 is located inside of housing 36 and includes notched post 46, chisel drive shaft 80, and a pinion 130, which is mounted on chisel drive shaft 80. When operating lever 12 is pulled, pinion 130 is rotated (by shaft 80) and moved along notched post 46. Pinion 130 has a plurality of extended portions 131 such that extended portions 131 engage the recessed portions of notched post 46. The interaction of pinion 130 and notched post 46 causes housing 36 to move downward, thereby feeding collet 16 and mortise chisel 17 (shown on FIG. 1) to a work piece. Pushing lever 12 causes the housing to move upward along post 46. Spring-loaded post 40 biases the housing (or “head”) 36 upward.

[0036] If operating lever 12 has been rotated to a point that it can be rotated no further, yet the mortise chisel has not reached the desired depth into the work piece, lever 12 can be reset to the substantially upright “top position” shown in FIGS. 1-4. This is accomplished by first securing the housing 36 using upper stop screw 51. Then, operating lever 12 and reciprocal engagement mechanism 30 are placed in the disengaged position 112 (i.e., by operating lever 12 outward as shown in FIG. 6). Lever 12 is then rotated in a generally upward direction to the “top position.” Operating lever 12 is then repivoted to the engaged position 110 (i.e., by pivoting inward as shown in FIG. 5). After the body 70 and coupling 72 are reengaged, stop screw 51 is loosened and handle 34 is again pulled in a generally forward and downward direction to further lower the collet 16 and chisel 17.

[0037] In disengaged position 112 (FIG. 6), operating lever 12 is moved such that handle 34 is moved in a direction generally away from motor 14, which moves terminal end 124 of lever insert 122 in a direction generally toward housing 36. This action causes operating lever 12 and lever insert 122 to deflect about pivot point 84. In this position, spring 78 is compressed along piston 114 and lever insert 122 pushes against channel 116 moving body 70 away from right coupling 72. When enough movement is accomplished, tooth grip 76 is disengaged, and space 132 is formed between body 70 and right coupling 72.

[0038] Referring to FIGS. 8 and 9, collet 16 has a chisel shank channel 136, a wall 134, a threaded chisel set hole 56, threaded set screw hole 54, a bottom side 142, and a lip 140. Chisel shank channel 136 is substantially round or elliptical in shape and preferably has a notch 138 that preferably extends the length of chisel shank channel 136. The notch 138 and/or elliptical shape of chisel shank channel 136 help to prevent a mortise chisel 17 from becoming “frozen” or “stuck” in collet 16 during and after use. Chisel set hole 56 is preferably aligned with notch 138. Lip 140 provides a surface to seat collet 16 to a rim on the housing 36 when a set screw is threadably inserted into set screw hole 54. FIG. 10 shows another collet 16′ for use with smaller chisel shanks. Collet 16′ has two bores of different centers drilled therein, thus producing an “elliptical-shaped” bore 136′.

[0039] To load the mortise chisel 17 into collet 16, the non-cutting (or shank) end of the chisel is inserted into chisel shank channel 136 such that, at a minimum, the top of the chisel is inserted beyond chisel set hole 56. Once the chisel has been completely inserted, a set screw (not shown) is inserted into chisel set hole 56 such that it presses tightly against the chisel shank.

[0040] The depth of a mortise cut is controlled by how deep mortise chisel 17 penetrates into a work piece. It is desirable to be able to consistently make multiple mortise cuts of the same depth. In order to facilitate multiple, equal-depth mortise cuts, depth stop 48 is used. As shown in FIGS. 1-4, depth stop 48 is cylindrical and fits snugly around notched post 46. Depth stop 48 has a depth screw 50, which is attached to depth stop 48. The desired location of depth stop 48 is attained by moving it along the length of notched post 46. Once in the desired location, depth stop 48 is secured in place by tightening depth screw 50 such that it rests tightly against notched post 46. Once in place, housing 36 is only able to descend until it makes contact with depth stop 48.

[0041] Prior to operating mortiser 10, a piece of wood, or work piece, is placed on table 18. The work piece is prevented from moving by placing it firmly against fence 22. Comers of the work piece may be held securely against table 18 through the use of conventional clamps. Once a work piece is securely in place, it can be moved from right to left (when the user is facing rack and pinion wheel 20) by turning rack and pinion wheel 20.

[0042] According to the invention, fence 22 may be an adjustable ram fence assembly that includes a block 144 having a threaded internal bore attached to the upper surface of base 38 (see FIG. 2), a fence adjust screw 52 having a fence end and a wheel end, the fence end in fixed contact with an equipment side of fence 22 and threadably connected to and passing through the threaded internal bore of block 144, and at least one ram assembly that includes two positive stops 23, 23′. A post 62 has an internal bore (not shown), a set screw hole (not shown), and a set screw with set screw handle 28. A cylindrical fence ram 26 is passed through the bore of post 62 and is attached to a collar 24 on fence 22.

[0043] In order that successive work pieces can be cut identically, fence 22 can be adjusted to accommodate a variety of depths along table 18. Fence 22 is moved by turning ram fence wheel 42. Fence adjust screw 52 extends from ram fence wheel 42 to fence 22. Fence adjust screw 52 is held in place by block 144 having a threaded, internal bore. When ram fence wheel 42 is turned, it causes fence adjust screw 52 to rotate and either push forward or pull rearward the fence 22.

[0044] Once fence 22 has been moved into position, it is firmly braced in place by fence rams 26. Set screw handle 28 on post 62 is tightened onto fence ram 26. This action holds fence ram 26 in place and, in turn, holds fence 22 in place. There can be one or more fence rams 26 to hold fence 22 in place. Preferably, there are two fence rams 26 as shown in the drawings.

[0045] In order to limit the forward position of fence 22, positive stops 23′ are positioned along rams 26 such that they are in contact with post 62 when the desired forward position of fence 22 is achieved. A stop set screw 27 is then tightened to secure the location of positive stop 23′ along ram 26. Once set screw 27 is tightened, ram fence wheel 42 will not be able to be turned to move fence 22 in the general direction of rack and pinion wheel 20, thus defining a set forward position of fence 22. Ram fence wheel 42 may, however, be turned to move fence 22 away from rack and pinion wheel 20. When the set forward position of fence 22 is desired, ram fence wheel 42 is turned until positive stops 23′ contact post 62. Likewise, stops 23 may be positioned to limit the rearward movement of fence 22.

[0046] The invention has been described with reference to the preferred embodiments. Obvious modifications and alterations will occur to others upon reading and understanding the preceding detailed description. For example, the mortiser may be provided with a right chisel coupling only, a left chisel coupling only, or (as shown) both. The various inventions herein may also be readily adapted to drill presses or the like. The present invention has been described with reference to specific details of particular embodiments thereof. It is not intended that such details be regarded as limitations upon the scope of the invention except insofar as and to the extent that they are included in the accompanying claims. 

I claim:
 1. A mortiser for making a mortise cut in a work piece comprising: a base; a table mounted on the base; a housing supported above the base; a collet connected with the housing for receiving a mortise chisel shank; a motor; a chisel drive shaft extending through the housing; a chisel drive coupling attached to the chisel drive shaft; a collet lowering mechanism connected with the chisel drive shaft; a reciprocal engagement mechanism capable of selectively engaging the chisel drive coupling; and an operating lever attached to the reciprocal engagement mechanism for rotating the chisel drive shaft and for reciprocating the reciprocal engagement mechanism into and out of engagement with the chisel drive coupling, whereby when the coupling and reciprocal engagement mechanism are engaged and an operator pulls the lever, the chisel drive shaft and the collet lowering mechanism cooperate to lower the collet toward the work piece.
 2. The mortiser of claim 1, wherein the collet includes a chisel shank removal device to prevent a chisel shank from becoming frozen or stuck in the collet bore.
 3. The mortiser of claim 1, wherein the reciprocal engagement mechanism and the chisel drive coupling include recessed portions and raised portions which may be intermeshed to engage the reciprocal engagement mechanism with the chisel drive coupling.
 4. The mortiser of claim 1, further including two chisel drive couplings attached to the left side and right side of the housing, respectively, to provide for left hand or right hand operation of the mortiser.
 5. The mortiser of claim 4, wherein the operating lever and reciprocal engagement mechanism may be selectively engaged and disengaged from the right hand and left hand chisel drive couplings.
 6. The mortiser of claim 1, wherein the reciprocal engagement mechanism comprises: a lever insert received in a cylindrical body; a piston carrying a spring, both housed in the cylindrical body, a protruding end of said piston being receivable in a bore on said chisel drive coupling; the lever insert having means for engaging an operating lever thereto; and the lever insert also having means for biasing the lever insert in an upright position.
 7. The mortiser of claim 6, wherein the means for biasing the lever insert include a threaded portion at an end of the lever insert, a nut threadably attached to the threaded portion, and a second spring carried on the lever insert and positioned between the nut and the lower side of the body.
 8. The mortiser of claim 6, wherein the spring housed in the cylindrical body is configured to bias the reciprocal engagement mechanism into engagement with the chisel drive coupling.
 9. The mortiser of claim 8, wherein the piston includes a head and said spring bears on said head.
 10. The mortiser of claim 1, wherein the base includes a rack and pinion mechanism, capable of moving the table in a left or right direction, comprised of a table pinion and a table rack, wherein the table pinion is in contact with and engaged with the table rack.
 11. The mortiser of claim 1 comprising an adjustable fence on an upper surface of the table.
 12. The mortiser of claim 11, wherein the adjustable fence comprises: a block having a threaded internal bore attached to the upper surface of the base; a fence adjust screw having a fence end and a wheel end, the fence end in fixed contact with an equipment side of the adjustable ram fence and threadably connected to and passing through the threaded internal bore of the block; and at least one fence ram assembly comprised of at least one positive stop slidably attached to a cylindrical ram, a post having an internal bore, a set screw hole, and a set screw with set screw handle, the cylindrical fence ram being journaled in the bore hole of the post and attached to the equipment side of the fence.
 13. The mortiser of claim 12 comprising two fence ram assemblies.
 14. The mortiser of claim 12 including two positive stops slidably attached to said cylindrical ram and positioned on either side of said post.
 15. The mortiser of claim 1, wherein the collet lowering mechanism comprises a pinion attached to said chisel drive shaft, the pinion engagable with a notched support post extending between said base and said housing.
 16. The mortiser of claim 1, wherein an accessory holder is attached to the rear side of the housing.
 17. A method of abrading a work piece using a motorized machine which is configured to vertically engage and disengage a cutting tool with the work piece, comprising the steps of: (a) positioning the work piece below the cutting tool; (b) engaging an operating lever with a drive coupling on the machine, the drive coupling mechanically interconnected with the cutting tool so as to permit upward and downward movement of the cutting tool; (c) lowering the cutting tool a first increment toward the work piece by pulling the lever from a first position to a second position; (d) disengaging the lever from the drive coupling; (e) repositioning the lever to the first position; (f) reengaging the lever with the drive coupling; and (g) further lowering the cutting tool a second increment by again pulling the lever from the first position to the second position.
 18. The method of claim 17, wherein the machine is a mortising machine and the cutting tool is a mortising chisel.
 19. The method of claim 17, wherein the operating lever carries a reciprocal engagement mechanism which has teeth that reciprocally engage with teeth on the drive coupling.
 20. The method of claim 17, wherein the operating lever is disengaged from the drive coupling by pivoting the operating lever outward.
 21. A mortiser for making a mortise cut in a work piece, comprising: a base; a table mounted on the base; a housing supported above the base; a collet mounted on the housing for receiving a mortise chisel shank; a motor; a mechanism for raising and lowering the collet; and the collet having a chisel shank removal device in an interior bore of the collet to facilitate removal of the chisel shank from the collet.
 22. The mortiser of claim 21, wherein the chisel shank removal device is a notch extending the length of the internal bore in the collet.
 23. The mortiser of claim 21, wherein the chisel shank removal device is an elliptical-shaped internal bore in the collet.
 24. A machine for abrading a work piece, comprising: a base; a table mounted on the base; a housing supported above the base; a mechanism for holding a cutting tool, extending downward from the housing; a motor; and an adjustable fence positioned on an upper surface of the table, with at least one fence ram assembly connected with the adjustable fence, wherein the fence ram assembly comprises at least one positive stop slidably attached to a cylindrical ram, a post having an internal bore, a set screw hole, and a set screw with set screw handle, the cylindrical fence ram being journaled in the bore of the post and attached to the rear side of the adjustable fence.
 25. The machine of claim 24, wherein the machine is a mortiser and wherein there are two fence ram assemblies positioned behind the adjustable fence.
 26. The machine of claim 24, including two positive stops slidably attached to the cylindrical ram, one positioned on either side of said post.
 27. A mortiser for making a mortise cut in a work piece, comprising: a base; a table mounted on the base; a housing supported above the base; a collet extending downward from the housing for receiving a mortise chisel shank, the collet having a device to facilitate removal of the chisel shank from the collet; a motor; a chisel drive shaft extending through the housing; a chisel drive coupling attached to the chisel drive shaft; a collet lowering mechanism connected with the chisel drive shaft; a reciprocal engagement mechanism capable of selectively engaging the chisel drive coupling; and an operating lever attached to the reciprocal engagement mechanism for rotating the chisel drive shaft and for reciprocating the reciprocal engagement mechanism into and out of engagement with the chisel drive coupling, whereby when the coupling is engaged and an operator pulls the lever, the chisel drive shaft and the collet lowering mechanism cooperate to lower the collet toward the work piece, and further including an adjustable fence positioned on an upper surface of the table, the adjustable fence having at least one fence ram assembly positioned behind the fence, the fence ram assembly comprising at least one positive stop slidably attached to a cylindrical ram, a post having an internal bore, a set screw hole, and a set screw with set screw handle, the cylindrical fence ram being journaled in the bore hole of the post and attached to the rear side of the adjustable fence. 